FAQs for Woodworking Tools and Woodworkers
General Lap-Sharp and Woodworking
Lap-Sharp Abrasives and Woodworking
Lap-Sharp Woodworking Accessories
The Lap-Sharp® has replaceable discs that allow the user to easily change abrasives grit sizes over a very wide range. Other sharpening systems use horizontally mounted grinding wheels that are limited to one or two grit sizes that are difficult to swap quickly and offer no way to dress the grinding wheel surfaces. The low speed of the Lap-Sharp® produces little friction heat and is activated by a footswitch, allowing the user to position the tool before starting the rotation of the abrasive. This provides the user much greater control of the tool and makes faceting and damage of the tool less likely.
The Lap-Sharp® provides a flat grind, rather than a hollow grind caused by the radius of a grinding wheel. A grinder is designed to only sharpen a bevel. With the Lap-Sharp® you can flatten the backs and sharpen the bevel all on one system. Grinders are also very limited in the grit sizes offered and will not provide a finished sharp edge. The Lap-Sharp® needs few if any attachments to sharpen most tools used by woodworkers. It needs no wheel dressing as do grinders. The low speed of the Lap-Sharp® produces little friction heat and is activated by a footswitch, allowing the user to position the tool before starting the rotation of the abrasive. This provides the user much greater control of the tool and makes faceting and damage of the tool less likely.
Starting with an abrasive grit size appropriate for the condition of the tool being sharpened, hold the tool in position; depress the footswitch to start the rotation of the abrasive disc. Once a flat surface is achieved, only a short period of abrasion of a subsequent grit size is needed before progressing to the next finer abrasive. Remove the disc securing knob, replace the disc with the next finer abrasive, and reinstall the securing knob. With the tool held in place, depress the footswitch to begin the next step in the sharpening process. Continue this process until the desired level of sharpness is achieved. When sharpening a bevel edge, repeat the above process, ending with a fine abrasive that may also be used to remove any wire edge that remains.
The low speed rotation, little friction heat generated, fine grit abrasives, ability to position the tool prior to starting the rotation of the abrasive disc, and control of starting and stopping the machine with a footswitch, make the Lap-Sharp®a very safe machine to operate. As with any moving machine, normal safety precautions should still be applied.
The Lap-Sharp®is manufactured in the USA with all high quality USA-manufactured components, to provide a long lasting and durable machine. The direct drive gear motor (for slow speed) has a hardened steel shaft that uses needle bearings, to support the significant load produced when pushing a tool at the outer edge of the eight-inch discs. The motor is temperature protected against damage and is reversible in rotation. It is designed for either 115 volt or 230 volt, 50Hz or 60Hz operation. The housing is cast aluminum with precision machined surfaces, not plastic; this provides a strong and durable structure for the machine components. The disc plates are manufactured to maintain their flatness, rather than by less-expensive methods that could cause distortion of the discs. The discs are anodized in different colors for ease in identifying the abrasive grits. Either side of these color coded discs can be used for mounting the PSA abrasives. The basic machine includes four interchangeable discs and six abrasive PSA discs. Few if any additional options are needed to achieve an extremely sharp edge in woodworking tools.
Depending on the condition of the tool being sharpened, it is possible to sharpen tools with as few as two or three abrasive grit sizes, just as is achieved with water stones. The Lap-SharpT is designed to address a wide variety of conditions of tools, so has abrasives that can take a rusty or poorly surfaced chisel or plane blade to a flat and near mirror finish. The user can decide how fine a finish is needed and limit the selection of abrasives to achieve that surface quality.
PSA discs have Pressure Sensitive Adhesive for ease in mounting them to the mounting surface such as the Lap-SharpT interchangeable color coded discs. A protective sheet is applied to the back of the abrasive that is removed to expose the adhesive surface. Only apply PSA backing to clean surfaces, as bumps in the abrasive surface can cause improper operation during the sharpening process. Hold the abrasive in a concave shape when applying the adhesive side to a disc surface. Slowly let the edges down so as to minimize the chance of trapping air bubbles under the abrasive. Using a "J" roller to apply pressure to the abrasive side and working the pressure from center to the outer edges will aid in achieving a smooth application of the abrasive disc.
RegalT is a micron graded CubitronT mineral electrostatically oriented and resin bonded onto high strength polyester film with a PSA coating on the back. This fast-cutting, durable abrasive generates precise, consistent finishes on hard-to-grind metal work pieces. We recommend this abrasive for initial phases of coarse sharpening both high carbon and HSS (High Speed Steel) blades. RegalT is durable, has excellent grit consistency, and can be used wet or dry. RegalT is available in 120µ, 80µ, and 60µ (=220 mesh) grits. Back to Top
TrizactT is an abrasive developed by 3M Corporation. These micron-graded abrasives are produced by micro-replication of microscopic three dimensional structures applied to a backing in a precise pattern. TrizactT consists of precisely shaped pyramids of fine grade mineral. As the tops of the pyramids wear away, new abrasive material is exposed. TrizactT can be used for abrading glass, Corian®, and for providing a fine and consistent finish when sharpening steel tools. It should be used wet, and can be washed off to prevent build up of amalgam in the pyramid valleys. Take care when sharpening narrow edge tools, to avoid causing a track of wear in the peaks of the abrasive surface.
TrizactT has a very consistent grit size, should be used wet, and lasts significantly longer than standard Aluminum Oxide abrasives. Due to its apex structure (like a pyramid), it can abrade steel tools longer since new abrasive is exposed as the peaks wear off and additional edges of abrasive are exposed. This occurs without quickly building lumps of amalgam that damage the finish of the surface being abraded. The amalgam collects in the valleys of the TrizactT rather than lumping on the surface. After using TrizactT until the amalgam partially fills the valleys, it can be scrubbed with a brush, some detergent, and water; cleaning the valleys and enabling the extended life of the abrasive.
Microfinishing film has a very high grit consistency to provide an evenly abraded surface. It is less expensive than TrizactT and can be used in the middle grades of abrasives used on the Lap-SharpT, without causing lumping of amalgam. In very fine grits (less than 20µ), they require constant flushing of the abrasive, to prevent abraded material and worn abrasive from scoring the finished surface of a tool. Microfinishing films have a thin film backing providing a flat abrasive surface that may be used wet or dry. They are fast cutting and an excellent choice for sharpening knives, carving tools, and turning tools. They will wear more quickly than TrizactT, but do not wear significant tracks into the abrasive surface when sharpening narrow tipped tools.
RegaliteT is a ceramic and aluminum oxide blend of abrasive on polyester backing. The grit sizes available are in 36, 50, 80, and 120 mesh. Normally used dry, these coarse abrasives are used when moderate amounts of metal must be removed. This abrasive is primarily used in sharpening planer and jointer knives, but can also be used for coarse abrading of other tools, stainless steel, or nickel alloys.
Silicon carbide is a sharp abrasive but breaks down very quickly. It then burnishes the tool rather than abrading it. This burnishing creases friction heat which can damage the tool's temper. This is easily demonstrated with two progressively smaller Silicon carbide abrasive sheets. Rub a steel tool on a piece of this abrasive paper, such as 400 grit. After working the tool for a short time, the tool will begin to shine. Next, rub the same tool area once or twice on a new piece of 500 grit paper. Note the scratches on the area that had been shining. The fresh but finer grit was abrading the area that had been burnished by the previous grit. A sharp tool is created by abrading the meeting edges of a tool to finely finished surfaces, not by buffing them till they are shiny. Silicon Carbide abrasive does not hold up as well as Aluminum Oxide. Silicon Carbide may be used successfully for abrading aluminum and other soft materials.
Diamond is a good but expensive abrasive that must be used with a continuous flow of lubricant (such as water). It lasts for a long time, but is only used in coarse (when applied to sharpening) grit sizes. Diamond does not provide a really fine finish for the final stages of sharpening due to the size of the mineral, so it is limited to initial stages of sharpening. Diamond will leave scratches in the surface of steel that should be removed with finer abrasives of Aluminum Oxide. It is primarily used for abrading carbide, glass, fiberglass, plastics, ceramics, and composites. Diamond discs are available in 120 and 220 ANSI mesh grades.
CBN is Cubic Boron Nitride. It is an expensive abrasive but is excellent for abrading steel, and is the preferred abrasive for cutting hard steel, when durability of the abrasive is a primary concern. It is recommended for abrading high-speed tool steels, die steel, hardened carbon steel, alloy steels, aerospace alloys, and abrasion-resistant ferrous metals.
It is available from Wood Artistry, L.L.C. as a special order item. E-mail email@example.com for availability and pricing information.
The polishing pack of abrasives provides finishes from 5 micron to 1 micron. It is comprised of 5 micron Trizact, and 3 and 1 micron Aluminum Oxide Polish Paper. This fine a finish is not always needed for achieving a sharp tool. How sharp a tool should be is determined by the person doing the sharpening. Hard steel tools hold a finer edge than softer steel tools. An 8000 grit water stone provides a 1.2 micron finish. The Lap-SharpT polishing pack is designed with a 1 micron polishing disc, to achieve an even finer finish.
Coated abrasives are used in production of abrasive papers and sanding discs that may have a variety of backing materials including paper, cloth and polyester film. The bonding material is a coating made of a synthetic resin bond (phenolic, alkyd or polyurethane resins). This holds the abrasive grit material to the backing material. Bonded abrasives are held together with glue like phenolic resins, and are used for grinding wheels and hard grinding discs and sharpening stones.
The numbering systems used to identify abrasive grits are designed to meet standards of different countries or are measured with different methods.
- Mesh Grades : The most common methods used in the USA are mesh grades, which are screens of mesh that abrasives can fall through. The finer the mesh, the smaller the grit size, so a 120 mesh is coarser than a 180 mesh.
- Micron sizing : With this system, the grit is measured in microns (one millionth of a meter), and a 120μ (micron) grit is finer than an 180μ grit.
- CAMI: The USA measurements are defined by " CAMI " ( Coated Abrasives Manufacturers' Institute).
- FEPA: European abrasives are defined by "FEPA" (Federation of European Producers of Abrasives). With this system, a P with the grit size indicates a coated abrasive while an F indicates a bonded abrasive.
- JIS: The Japanese system for measuring abrasives is defined by a "JIS" (Japanese Industrial Standard) document.
- Note: Cross references are made by several sources, but do not always agree, as there is not an exact equivalent of all abrasive grades. One listing of an 8000 grit water stone equates it to 3μ while another says it is 1.2μ. CAMI 360 mesh grit is listed as being 28.80μ, while a FEPA P360 and JIS 360 are listed at 40.50μ. The numbers do not always equate to other measurement systems.
The tool guide bar and tool clamp may be used to assist the user in maintaining the desired bevel angle when sharpening thin blade tools. It is not needed for the flat side of tools. Tools with large surface areas on their bevels, such as Japanese plane blades and many cast steel blades, have enough surface area for the user to hand hold the tool at the proper bevel angle without the use of a guide. When sharpening tools such as thin modern plane blades, the guide bar can assist the user in maintaining the bevel angle, especially when the tool is removed from the machine surface such as when interchanging abrasive discs.
In addition to the Tool Guide Bar and tool clamp, a Planer and Jointer knife jig for use in sharpening knives to 25 inches in length (or two 12” knives at a time), a jig and bar combination for sharpening both carving and turning tools, (even with a fingernail profile) and a compound honing guide that may be used with both Western and Japanese chisels and plane irons are available. In addition to these jigs, a splash guard is available to reduce spray emitted from the spinning abrasive disc when lubricant is used.